Cryogenic storage tanks

ABSTRACT

A cryogenic storage tank for the storage of low temperature liquids, such as liquefied petroleum gas or liquefied natural gas for example, at or about atmospheric pressure and of the kind having a double-skinned wall whose cavity is packed with insulating material, and characterised in that a non-toxic noncombustible gas is stored at an elevated pressure in a chamber defined by the cavity between the inner and outer skins of the side wall of the tank.

United States Patent [191 Turner NOV. 18, 1975 1 1 CRYOGENIC STORAGE TANKS [75] Inventor: Frederick Henry Turner, Reading,

England [73] Assignee: Simon-Carves Limited, Stockport,

England [22] Filed: Nov. 5, 1973 21 Appl. No.: 412,894

[30] Foreign Application Priority Data Dec. 2, 1972 United Kingdom 55757/72 [52] US. Cl. 62/45; 220/9 LG; 220/15 [51] Int. Cl. F17C 1/02 [58] Field of Search 62/45, 54; 220/9 B, 9 C, 220/9 LG, 15, 88 B; 52/245, 249, 405, 406;

[56] References Cited UNITED STATES PATENTS 1,533,309 4/1925 Durborow 220/88 B 2,153,555 4/1939 Gallery 220/88 B 2,406,540 8/1946 Harrington 62/54 X 2,601,763 7/1952 Peff 62/54 2,777,295 1/1957 Bliss 6t 211 52/249 X 2,916,889 12/1959 Sflttler i i A i r i. 62/55 2,999,366 9/1961 LaFave 6t 2.20/9 LG 3,191,395 6/1965 Maher et al, .1 62/54 Primary Examiner-william F. ODea Assistant E.\'aminerRonald C. Capossela Attorney, Agent, or Firm-Norris & Bateman [57] ABSTRACT A cryogenic storage tank for the storage of low temperature liquids, such as liquefied petroleum gas or liquefied natural gas for example, at or about atmospheric pressure and of the kind having a doubleskinned wall whose cavity is packed with insulating material, and characterised in that a non-toxic non- .combustible gas is stored at an elevated pressure in a chamber defined by the cavity between the inner and outer skins of the side wall of the tank.

18 Claims, 2 Drawing Figures U.S Patent Nov. 18, 1975 3,919,855

CRYOGENIC STORAGE TANKS This invention concerns cryogenic storage tanks for the storage of low temperature liquids, such as lique' fied petroleum gas or liquefied natural gas for example, at or about atmospheric pressure and of the kind having a double-skinned side wall whose cavity is packed with insulating material.

According to the present invention, a cryogenic storage tank of the kind referred to, is characterized in that a non-toxic non-combustible gas is stored at an elevated pressure in a chamber defined by the cavity between the inner and outer skins of the side wall of the tank.

The invention will be further apparent from the-following description with reference to the figures of the accompanying drawing which show, by way of example only, one form of cryogenic storage tank embodying the invention.

Of the drawing:

FIG. 1 shows a diagrammatic partially cut-away perspective view of the tank; and

FIG. 2 shows a detailed cross-section through part of the tank of FIG. 1, and on an enlarged scale.

Referring now to the drawing, it will be seen that the cryogenic storage tank is essentially comprised by an insulating circular base generally indicated at 10, a cylindrical side wall comprised by inner and outer skins 11 and 12 respectively defining a cavity 13 therebetween, and a domed roof generally indicated at 14.

In a preferred arrangement both the inner and outer skins l1 and 12 of the cylindrical wall are formed from concrete. The inner skin 11 is pre-stressed so as to place it initially in compression and the outer skin 12 may be reinforced or pre-stressed.

As best seen from FIg. 2, upper and lower annular seals 15 and 16 are provided between the inner and outer skins 1 1 and 12 at the top and bottom of the side wall respectively. Preferably the seals 15 and 16 are formed from flexible stainless steel members of U- shaped cross-section. The cavity 13 between the inner and outer skins 11 and 12 of the side wall is packed with a powdered insulant such as exfoliated mineral ore to reduce leakage of heat into the interior of the tank.

A line 17 communicates with the annular chamber defined between the inner and outer skins 11 and 12 of the side wall and the upper and lower seals 15 and 16 via a stop valve 18, by means of which the chamber aforesaid can be pressurized with a non-toxic non-combustible gas, such as nitrogen or carbon dioxide for example. In principle there is no upper limit to the pressure of this gas in the chamber although in practice an upper limit of about atmospheres might be imposed by considerations of economy.

Pipes 19 are provided and extend downwardly through the roof 14 at a plurality of circumferentially spaced intervals therearound. Each pipe U communicates with the pressurized chamber through the upper seal member via an expansion bellows and filter 20. Each of the pipes 19 vents to atmosphere via a pressure-relief valve 21.

In known manner the domed roof 14 of the tank incorporates a plurality of safety valves 22 for the relief of pressure from the interior of the tank should any pressure surge occur, as for example, in the event of fire or for any other reason.

In accordance with a preferred feature of the invention a line 23 is led from each of the outlet pipes from the interior of the tank to the safety valves 22 to an associated one of the pipes 19 via an expansion bellows 24 and remotely operable valve 25. Each line 23 communicates with its pipe 19 at a position beneath the pressure-relief valve 21.

It will be understood that the provision of the inert gas under pressure in the cavity between the inner and outer skins 11 and 12 of the side wall prevents leakage of gas outwardly from the interior of the tank. Any leakage which does occur will be inward and there is no objection to this. Of course a pressure is applied outwardly to the outer skin 12 which may, as indicated above, pre-stressed to resist such, or may be treated with a flexible inner lining or membrane 26 to ensure that it remains gas-tight. Should any leaking occur, however, it would lead only to the excape of inert gas thus presenting no safety hazard.

The valves 25 are arranged to be opened either manually (from a remote position) or automatically in the event of the safety valves 22 opening. Thus in the event of the safety valves 22 opening a relatively high volume of inert gas is mixed in with the escaping flammable gas thereby minimizing the risk of fire of explosion.

It will be appreciated that it is not intended to limit the invention to the above example only, many variations, such as might readily occur to one skilled in the art, being possible without departing from the scope thereof, as defined by the appended claims.

Thus, for example the outer skin of the side wall of the tank need not be of concrete construction but may be formed from steel sheets.

What is claimed is:

l. A cryogenic storage tank including a side wall comprising an inner skin defining a low temperature liquid tank interior for storing said low temperature liquid at about atmospheric pressure, an outer skin forming an exterior wall of said tank, and means for preventing leakage of contents from said tank interior through said inner skin comprising a chamber defined by said inner and outer skins and a quantity of a non-toxic noncombustible gas stored at sufficiently above atmospheric pressure in said chamber to assure that any leakage occuring through said inner skin is only gas from said chamber to the contents in said tank interior and that leakage of contents from said tank interior through said inner skin is prevented due to the pressure of said gas between said inner and outer skins of the side wall of the tank.

2. A cryogenic storage tank according to claim 1 wherein said gas is carbon dioxide.

3. A cryogenic storage tank according to claim 1 wherein said gas is nitrogen.

4. A cryogenic storage tank according to claim 1 wherein said gas is stored at a pressure of up to ten atmospheres.

5. A cryogenic storage tank according to claim 1 wherein upper and lower seals are provided between the inner and outer skins of the side wall of the tank to define said chamber.

6. A cryogenic storage tank according to claim 5 wherein each said seal is formed from flexible stainless steel and is of U-shaped cross-section.

7. A cryogenic storage tank according to claim 1 wherein at least one pipe extends from said chamber and vents to atmosphere via a pressure-relief valve.

8. A cryogenic storage tank according to claim 6 wherein at least one pipe extends from said chamber and vents to atmosphere via a pressure-relief valve.

9. A cryogenic storage tank according to claim 1 wherein at least one line extends from the interior of said tank and vents to atmosphere via a normally closed safety valve, there being a pipe extending from said chamber to said line via valve means.

10. A cryogenic storage tank according to claim 6 wherein at least one line extends from the interior of said tank and vents to atmosphere via a normally closed safety valve, there being a pipe extending from said chamber to said line via valve means.

11. A cryogenic storage tank according to claim 7 wherein at least one line extends from the interior of said tank and vents to atmosphere via a normally closed safety valve, there being a pipe extending from said chamber to said line via valve means.

12. A cryogenic storage tank according to claim 9 wherein said valve means is manually operable from a remote position.

13. A cryogenic storage tank according to claim 9 wherein said valve means is automatically operable so as to be opened when the contents of the interior of the tank are venting through said safety valve.

14. A cryogenic storage tank according to claim 1 and being of circular horizontal cross-section.

15. A cryogenic storage tank according to claim 14 wherein both the inner and outer skins of the side wall of the tank are formed from concrete.

16. A cryogenic storage tank according to claim 15 wherein the inner skin is pre-stressed.

17. A cryogenic storage tank according to claim 15 wherein the outer skin is reinforced.

18. A cryogenic storage tank according to claim 15 wherein the outer skin is pre-stressed. 

1. A cryogenic storage tank including a side wall comprising an inner skin defining a low temperature liquid tank interior for storing said low temperature liquid at about atmospheric pressure, an outer skin forming an exterior wall of said tank, and means for preventing leakage of contents from said tank interior through said inner skin comprising a chamber defined by said inner and outer skins and a quantity of a non-toxic noncombustible gas stored at sufficiently above atmospheric pressure in said chamber to assure that any leakage occuring through said inner skin is only gas from said chamber to the contents in said tank interior and that leakage of contents from said tank interior through said inner skin is prevented due to the pressure of said gas between said inner and outer skins of the side wall of the tank.
 2. A cryogenic storage tank according to claim 1 wherein said gas is carbon dioxide.
 3. A cryogenic storage tank according to claim 1 wherein said gas is nitrogen.
 4. A cryogenic storage tank according to claim 1 wherein said gas is stored at a pressure of up to ten atmospheres.
 5. A cryogenic storage tank according to claim 1 wherein upper and lower seals are provided between the inner and outer skins of the side wall of the tank to define said chamber.
 6. A cryogenic storage tank according to claim 5 wherein each said seal is formed from flexible stainless steel and is of U-shaped cross-section.
 7. A cryogenic storage tank according to claim 1 wherein at least one pipe extends from said chamber and vents to atmosphere via a pressure-relief valve.
 8. A cryogenic storage tank according to claim 6 wherein at least one pipe extends from said chamber and vents to atmosphere via a pressure-relief valve.
 9. A cryogenic storage tank according to claim 1 wherein at least one line extends frOm the interior of said tank and vents to atmosphere via a normally closed safety valve, there being a pipe extending from said chamber to said line via valve means.
 10. A cryogenic storage tank according to claim 6 wherein at least one line extends from the interior of said tank and vents to atmosphere via a normally closed safety valve, there being a pipe extending from said chamber to said line via valve means.
 11. A cryogenic storage tank according to claim 7 wherein at least one line extends from the interior of said tank and vents to atmosphere via a normally closed safety valve, there being a pipe extending from said chamber to said line via valve means.
 12. A cryogenic storage tank according to claim 9 wherein said valve means is manually operable from a remote position.
 13. A cryogenic storage tank according to claim 9 wherein said valve means is automatically operable so as to be opened when the contents of the interior of the tank are venting through said safety valve.
 14. A cryogenic storage tank according to claim 1 and being of circular horizontal cross-section.
 15. A cryogenic storage tank according to claim 14 wherein both the inner and outer skins of the side wall of the tank are formed from concrete.
 16. A cryogenic storage tank according to claim 15 wherein the inner skin is pre-stressed.
 17. A cryogenic storage tank according to claim 15 wherein the outer skin is reinforced.
 18. A cryogenic storage tank according to claim 15 wherein the outer skin is pre-stressed. 